MESA BOOGIE
20/20
Owner's Manual
The Spirit of Art in Technology
1317 Ross Street Petaluma, CA 94954
USA
Hello from the Tone Farm...
YOU, the smart player and all around intuitive human, have put your trust in us to be
your amplifier company. This is something we do not take lightly. Our reward is that
we've made a classic amplifier and by choosing this amplifier, you have become part of
the MESA family...Welcome! Our goal is to never let you down. Your reward is that you
are now the owner of the all new 20/20 power amp, bred of fine all tube amp
heritage...benefiting from the many patented pioneering MESA/Boogie circuits that led to
the refinement of your new instrument. Feel confident, as we do, this product will
inspire many hours of musical satisfaction and lasting enjoyment. It was built with you
in mind, by players who know the value of a fine musical instrument and the
commitment it takes to make great music. The same commitment to quality, value and
support we make to you...our new friend.
20/20
TABLE OF CONTENTS
Precautions
Overview ________________________________________________________________________ 1
Instant Gratification Hook-Up _______________________________________________________ 2
FRONT PANEL CONTROLS:
Presence ________________________________________________________________________
Volume __________________________________________________________________________
Power ___________________________________________________________________________
Standby _________________________________________________________________________
Fuse ____________________________________________________________________________
3
3
3
3
4
REAR PANEL FEATURES:
Instrument Input A / B _____________________________________________________________ 4
Speaker Jacks __________________________________________________________________ 4 / 5
Slave ____________________________________________________________________________ 5
Tube Task Chart __________________________________________________________________ 6
Personal Setting Pages ____________________________________________________________ 7
Parts Sheet ______________________________________________________________________ 8
Your Mesa/Boogie Amplifier is a professional instrument. Please treat it with respect and operate it properly.
USE COMMON SENSE AND ALWAYS OBSERVE THESE PRECAUTIONS:
Do not expose amplifier to moisture, rain or water, direct sunlight
or extremely high temperatures.
Always insure that amplifier is properly grounded.
Always unplug AC power cord before changing fuse or any
tubes.
When replacing fuse, use only same type and rating.
Avoid direct contact with heated tubes.
Insure adequate air circulation behind amplifier.
Keep amplifier away from children.
Be sure to connect to an AC power supply that meets the power
supply specifications listed on the rear of the unit.
If there is any danger of lightning occurring nearby, remove the
power plug from the wall socket in advance.
To avoid damaging your speakers and other playback equipment,
turn off the power of all related equipment before
making the connections.
Do not use excessive force in handling control buttons, switches
and controls.
Remove the power plug from the AC mains socket if the unit is to
be stored for an extended period of time.
Do not use solvents such as benzene or paint thinner to clean
the unit. Wipe off the exterior with soft cloth.
Be sure to have the warranty card filled out by the store at which
you purchased this product and send back to Mesa Engineering.
YOUR AMPLIFIER IS LOUD! EXPOSURE TO HIGH SOUND VOLUMES MAY CAUSE
PERMANENT HEARING DAMAGE!
No user serviceable parts inside. Refer service to qualified personnel. Always unplug AC power before
removing chassis.
EXPORT MODELS: Always insure that unit is wired for proper voltage. Make certain grounding conforms
with local standards.
READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.
20/20
Operating Instructions
OVERVIEW:
Congratulations ...you have just become the owner of the most “Tone Full” one and three quarters inches of rack guitar
power available on todays’s market. Don’t let the one rack space size fool you - this small amp packs a BIGGER than life
voice and has been designed to handle all of what you’d expect and probably more from an amp this size. Though it weighs
in at 20 watts per channel, gruelling tone and headrooom test confirm its authority even against amps boasting twice its
rated power and yes...bulk. As with many of its Boogie cousins - the concept “Shrink the package - Enlarge the Tone” was
in full effect here. If you’ve already played your 20/20, you know how incredibly big and bold, sweet and juicy it sounds...if
you chose it by reputation alone, stop! Put this owner’s manual down and a second, connect it to your preamp (hopefully
one of our Mesa products) and favorite speaker cabinets (again, hopefully a Mesa product.) Begin the tonal experience so
many 20/20 owners rave about immediately! Don’t wait! One chord and one note will tell you more about this amp than we
could ever say here in print. Besides, you can come back and read this the day after tomorrow - when your finger’s are too
sore to play anymore - and you can better enjoy this manual with a blown mind and your previous idea of tone well rocked!
The 20/20’S power sections are fueled by two pairs of EL-84 power tubes wired for Dyna-Watt response which unlease
touch-sensitive dynamic punch far in excess of their twenty watt per channel rating. This is what happens when DynaWatt’s stored energy is released like a camera flash and controlled by your picking technique/style. With enough fan cooled power to cover small venues, the 20/20 can also double as the power-amp “tone generator” in bigger rigs. The Two
Stereo Slave jacks located on the Rear Panel marked SLAVE A - B allow you to capture the sound of a great small amp’s
musical clip. Two speaker jack combinations have been provided...two 8 Ohm (left & right) and two pairs of 4 Ohm jacks
(respectfully labled left & right) ensure the proper impedance match to many types of speaker enclosures.
While remaining straight forward and simple to operate, the 20/20 All Tube Stereo power amplifier is sure to measure up
to all your musical expectations and provide you with many hours of toneful bliss. Thanks again for letting us be part of
your musical journey, Enjoy!
FRONT VIEW: 20/20
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
1A SB
SB
REAR VIEW: 20/20
A
INPUT A
B 8 OHMS 4 OHMS 4 OHMS B SLAVE
PAGE 1
STANDBY
VOLUME
PRESENCE
EL-84 ALL TUBE STEREO
HANDBUILT IN USA
Instant Gratification Basic Hook-Up Diagram:
Front Panel of Mesa/Boogie Formula Pre-Amp
IN
FT.SW.
GAIN
RHYTHM
RECORD
LO GAIN
EQ
EQ IN
GAIN
FT
MASTER SW
BASS
MID
TREBLE
LD2
IN
HI GAIN
MESA BOOGIE
LEAD 1
60Hz
240
750
2200
6600
O
U
T
P
U
T
MASTER
RHYTHM
ON
LEAD 2
AC
LD
1
FT
SW
Formula Pre
SHIELDED CABLE
Back Panel of Mesa/Boogie Formula Pre-Amp (partial view)
117 V~
1 AMP
60 HZ.
ESA BOOGIE
M
CIRCUIT PATENTS PENDING
LIFT
100%
10%
GROUND
RETURN - L
LD1 - LD2
FX SEND
RHY - LD
EXT
SW
FX MIX
RETURN - R
EQ
LEFT
EXT
SW
REC
OUT
TIP
RING
SLEEVE
RIGHT
MAIN
OUT
HANDMADE IN CALIFORNIA
SHIELDED CABLE
STEREO EFFECTS UNIT
IN
MIDI OUT
SHIELDED CABLE
INPUTS
OUTPUT
LEFT
RIGHT
LEFT
RIGHT (MON0)
AC POWER
Rear Panel of 20/20 Power Amp (partial view)
A
INPUT B
8 OHMS
4 OHMS
4 OHMS
A SLAVE
B
SPEAKER CABLE
UNSHIELDED
SPEAKER CABLE
UNSHIELDED
SPEAKER B
SPEAKER A
PAGE 2
FRONT PANEL CONTROLS:
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
PRESENCE:
POWER
PATENTED 4,713,624
PRESENCE
FUSE
PRESENCE
VOLUME
POWER
1A SB
SB
STANDBY
VOLUME
PRESENCE
EL-84 ALL TUBE STEREO
HANDBUILT IN USA
These controls “open-up” the 20/20 producing brightness and sparkle for clean sounds at higher settings
or sizzle and edge when set high for distortion sounds. At lower PRESENCE Control settings you can darken and compress lead sounds
making them warmer and fatter. Turning the PRESENCE Controls to
EL-84 A
zero “chokes the brights” completely, making the 20/20 great for jazz
clean sounds or round vocal lead work.
VOLUME
VOLUME
PRESENCE
VOLUME: These two potentiometers (pots) control the volume level of each side or channel of the 20/20. Since there’s
only one Standby switch on this unit, these two controls may be used as channel muting controls.
POWER
PATENTED 4,713,624
PRESENCE
VOLUME
NOTE: If only one speaker is to be used on one channel and no
speaker load is present on the other, always turn the unused channels VOLUME Control to zero. To prevent oscillation (motorboating
like sound) turn the PRESENCE Control of that channel all the way
up.
VOLUME
PRESENCE
EL-84 A
These two toggles located next to the 20/20’s left and right channel VOLUME Controls deliver
A.C. Mains voltage and D.C. filament voltage. When powering up cold - make sure the STANDBY switch is in the Standby
position when flipping the POWER switch to the ON position. Wait at least 30 seconds before flipping the STANDBY switch
to the ON position. This procedure reduces shock on cold tubes and prolongs their toneful
tube life. Remembering to use the STANDBY switch on set breaks also prolongs tube life.
POWER & STANDBY:
2A SB
NOTE: Power tube life varies depending on many factors i.e. how much you play, how
you treat your equipment etc. We’ve found that most discerning pro’s who use their gear
five to seven nights a week start noticing some tone loss somewhere around 8 months to a year. Some people, however,
use the same set of power tubes for years with no complaints.
FUSE
VOLUME
POWER
1A SB
SB
STANDBY
VOLUME
We recommend changing your power tubes once a year if you play alot. This way you’re ensured of smooth operation and
optimum tone. Always use Mesa power tubes of matching color codes whenever possible. These are matched correctly
with each other and hammer tested and actually cost less than the so called matched competitors in most cases. Also, it
keeps your 20/20 warranty intact.
PAGE 3
FRONT PANEL CONTROLS:
(Continued)
FUSE: This is the A.C.’s (Alternating Current) main fuse and provides protection from outside A .C. fluctuations as well as power
tube failure damage. Should the fuse blow, replace it with the same rating in a Slo-Blo type package. The domestic U.S. version
requires a 2 amp Slo-Blo fuse. A power tube short or failure is often the cause of a blown fuse...Follow
the cold start procedure mentioned in the POWER & STANDBY switch section and watch the
power tubes as you flip the STANDBY switch to the ON position. If a power tube is going bad or
is arcing you will see it! Flip the STANDBY switch to Standby immediately and replace the faulty
power tube and the fuse if necessary. If you see nothing abnormal as you lift the STANDBY
switch, it is possible that a power tube shorted temporarily and blew the fuse. If this is the case it may work again normally. To be extra
safe, you might want to replace just the adjacent tube or all power tubes in the “shotgun” troubleshooting tradition and save t he
replaced set as spares. Spare fuses are a must for the fabled cord bag along with your spare tubes. Always carry both for they could
be worth their weight in gold someday.
2A SB
FUSE
VOLUME
POWER
1A SB
SB
STANDBY
VOLUME
Now that we’ve reviewed the 20/20’S Front Panel controls and found its simple layout to be easily digested, let’s move aft for a review
of the Rear Panel connections.
REAR PANEL:
A
INPUT A
B 8 OHMS 4 OHMS 4 OHMS B SLAVE
INPUTS A / B: Located to the far left (when facing the unit from the rear) you’ll find two 1/4” insulated jacks. These are the inputs
for preamps and/or effects, depending on how you wire your system. You may drive the 20/20 with your preamp directly or choose
to come from the last effect in a chain and drive the power amp this way.
Either way is fine and up to your preference.
A
INPUT B
8 OHMS
4 OHMS
4 OHMS
A SLAVE
B
SPEAKERS: These six jacks deliver the 20/20’S incredible tone to your favorite speaker cabinets. One eight Ohm and two four
Ohm jacks per channel are provided. Use one eight Ohm cabinet in the eight Ohm jack of each channel and two eight Ohm cabinets
into the two four Ohm jacks per channel. Use one four Ohm cabinet into one
four Ohm jack (each channel). Use one sixteen Ohm cabinet into the eight
Ohm jack (each channel). Two sixteen Ohm cabinets connected with a “Y”
cable works even better in the eight Ohm jack, once again this would be the
same for each channel.
A
INPUT B
8 OHMS
4 OHMS
4 OHMS
A SLAVE
B
Don’t forget: Duplicate the proper load for both channels: Turn its VOLUME Control to zero and its PRESENCE Control all the
way up. It’s also best not to send signal to the unused channel input.
PAGE 4
REAR PANEL:
(Continued)
SPEAKERS: (Continued) Speaker cabinets may be 4, 8 or 16 Ohms and can vary from one manufacturer to another. If you are
not sure of the impedance rating of your cabinet, you may need to remove the cabinet’s rear panel in order to verify the impedance
rating of the speaker (s). Mesa/Boogie 4x12 and 4x10 cabinets come standard wired to 8 Ohms and are wired in series-parallel. No
matter how unusual your speaker setup, it is always possible to get good performance from your 20/20.
SLAVE A / B: The 20/20 provides a pair of slave jacks that enable you to capture the sound of this magic little power section and
inject it directly into outboard effects processors or other larger power amplifiers for higher output at larger venues. In either of these
scenarios the 20/20 becomes a tone generator that enables you to achieve the sound of a small amp cranked, in a one space
rackable format. Due to space considerations, the output levels are preset at the slave output jacks to provide an optimum level when
the Front Panel VOLUME Controls are set to approximately 10:30, which is usually just past the onset of clip - depending on the
strength of the signal at the Inputs.
This predetermined level of the Slave jacks should be well matched to most applications and some control of the signal level is
possible by adjusting the Front Panel VOLUME Controls. If you have an application where you are using the 20/20 at either super
low or extremely high for fully clipped sounds, you can call us and ask for a Product Specialist and he can figure out a signal strength
resistor network for your individual needs and can send the parts to you for a technician in your area to install. Most likely though, by
working with the 20/20’s VOLUME Controls in conjunction with the input attenuators of the processor or power amp you are interfacing with, a Slave level can be obtained that will work well for your situation. Please try this before calling us to modify your amp.
NOTE: WARNING ! - A load must be connected at all times to the Speaker Outputs when using the Slave jacks. If you intend to use
the 20/20 as a tone generator only and do not want to listen to the live speaker outputs, connect a load resistor with a rating of at least
40 watts (or greater if driven continuously into clip) and with a 4 or 8 Ohm impedance rating. Each channel must have a load resistor
connected to its proper speaker jacks. In most cases a speaker will deliver better sound and a tone you are more familiar with due
to the reactive nature of a speakers dynamic signature and natural compression. If you prefer this Slave sound, but don’t want to listen
to the live speaker simply put it in a box or hide it under the drum riser...etc.
PAGE 5
TUBE LAYOUT and TASKS
20/20
REAR PANEL (cut-a-way view looking down from the top of unit)
MESA
MESA
MESA
MESA
MESA
12AX7A
12AX7A
12AX7A
12AX7A
12AX7A
V7
V5
V6
V4
V3
MESA
MESA
12AX7A
12AX7A
V2
V1
THESE 4 TUBES
LEFT
SIDE
12AX7
EL-84
12AX7
RIGHT
SIDE
TUBE ASSIGNMENT
V1 - A = Channel B Input Stage
V1 - B = Channel A Input Stage
V5 =
V6 =
V2 - A =
V2 - B =
V7 - A =
V7 - B =
V3 =
V4 =
Phase Inverter for Channel B
Power Tubes for Channel A
Phase Inverter for Channel A
Power Tubes for Channel B
DIMENSIONS & SPECIFICATIONS
WEIGHT: shipping weight 20 lbs.
HEIGHT: 1 rack unit - 1 3/4 nches
DEPTH: 13 inches ( over all - including knobs )
INPUT IMPEDANCE:
POWER REQUIREMENTS: (from AC mains) 117 volts
PAGE 6
PAGE 6
20/20
Personnal Settings Page
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
1A SB
EL-84 ALL TUBE STEREO
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
SB
STANDBY
VOLUME
PRESENCE
HANDBUILT IN USA
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
1A SB
EL-84 ALL TUBE STEREO
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
1A SB
EL-84 ALL TUBE STEREO
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
1A SB
EL-84 ALL TUBE STEREO
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PRESENCE
VOLUME
POWER
PRESENCE
VOLUME
POWER
1A SB
PRESENCE
VOLUME
POWER
1A SB
1A SB
EL-84 ALL TUBE STEREO
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
EL-84 ALL TUBE STEREO
2A SB
20/20 DYNA-WATT POWER
PATENTED 4,713,624
FUSE
PAGE 7
EL-84 ALL TUBE STEREO
Parts Sheet - 20 / 20 - Front Panel
LIGHT
Pt # 395620
20/20 DYNA-WATT POWER
PATENTED 4,713,624
KNOBS (BOTH)
Pt # 408111
POT Pt#
POT Pt#
592151
592151
PRESENCE
VOLUME
POT Pt#
2A SB
POWER
SWITCH
Pt # 601073
1A SB
SB
STANDBY
POT Pt#
592151
592151
VOLUME
PRESENCE
FUSE
SWITCH
Pt # 601073
EL-84 ALL TUBE STEREO
HANDBUILT IN USA
KNOBS (BOTH)
Pt # 408111
PAGE 8
FUSE CAP
Pt # 790347
Parts Sheet - 20 / 20 - Rear Panel
A
INPUT B
8 OHMS
4 OHMS
4 OHMS
ALL JACKS
Pt# 613111
A SLAVE
B
MESA BOOGIE
The Spirit of Art in Technology
Thank you
for trusting MESA/Boogie to be your amplifier
company. We wish you many years of toneful enjoyment from
this handbuilt all tube instrument.
The Spirit of Art in Technology
1317 Ross Street Petaluma, CA 94954
USA
Phone No. 707-778-6565 FAX No. 707-765-1503